Dibenzimidazole compounds

ABSTRACT

ARE HIGHLY EFFICACIOUS GREASE THICKENING AGENTS.   WHEREIN R1 and R2 are aliphatic hydrocarbyl radicals, R3 is a hydrocarbylene radical, R4 and R5 are aromatic hydrocarbylene radicals and X is -O- or   Dibenzimidazole compounds corresponding to the formula:

United States Patent 1191 Birke I 1451 Apr. 29, 1975 DIBENZIMIDAZOLE COMPOUNDS [75] Inventor: August l-l. Birke, Godfrey, ll].

[73] Assignee; Shell Oil Company, New York, N.Y.

[22] Filed: Sept. 27, 1973 [21] Appl. No.: 401,516

Related US. Application Data [60] Division of Ser. No. 296,733, Oct. ll, i972, Pat. No. 3,785,979, which is a continuation-in-part of Scr. No. 169,459, Aug. 5, 1971, abandoned.

[52] US. Cl. 260/3092 [51] Int. Cl Cl0m 5/20 [58] Field of Search 260/3092 [56] References Cited UNITED STATES PATENTS 3.105.837 10/1963 Ursprung 260/3092 3,752,765 8/1973 Birkc 252/515 A 3,785,979 l/l974 Birkc 252/515 A Primary Examiner-Henry R. Jiles Assistant Examiner-C. M. S. .laisle Attorney. Agent, or Firm--Henry C. Geller [57] ABSTRACT Dibenzimidazole compounds corresponding to the formula:

wherein R, and R are aliphatic hydrocarbyl radicals, R is a hydrocarbylene radical, R and R are aromatic hydrocarbylene radicals and X is -O-- or are highly efficacious grease thickening agents.

8 Claims, No Drawings 'DIBENZIMIDAZOLE COMPOUNDS CROSS-REFERENCE TO RELATED APPLICATIONS This is a division of application Ser. No. 296.733. filed Oct. II. 1972. now US. Pat. No. 3.785.979, patented Jan. 15. 1974. which application is a continuation-in-part of copending US. application Ser. No. 169,459. filed Aug. 5. l97l. now abandoned.

BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to a novel class of dibenzimidazole compounds and grease compositions gelled therewith.

SUMMARY OF THE INVENTION It has now been found that grease compositions having excellent high temperature lubricating properties can be produced by incorporating into an oleaginous base vehicle. a minor amount of a dibenzimidazole compound corresponding to the formula:

2. Description of the Prior Art It has become increasingly important that grease composition be able to provide adequate lubrication at high temperatures. e.g.. temperatures of 350F to 450F or higher. Numerous thickening agents have been proposed for use in such greases. including soap base thickeners, inorganic clay thickeners and organic thickening agents. Examples of this latter class of thickening agents include various polyureas. ureido compounds, aminoaryl diureas. triazines and the like. Such organic thickening agents are typically prepared by reacting one or more mono-. di. or polyamines with one or more mono-. di-. or polyisocyanates. Other related organic thickeners include arylcarbamyl compounds formed by reacting an aromatic amine with the reaction product of an aromatic diisocyanate and paminobenzoic acid.

While organic thickening agents of the aforementioned types produce greases having desirably high dropping points, this is but one measure of a greases ability to perform satisfactorily at high temperatures. Other important properties include thermal and mechanical stability. high temperature bearing performance. oxidation and corrosion resistance, etc. While additives are normally incorporated into grease compositions to improve one or more of these properties, the thickening agent itself can significantly affect. either favorably or adversely, the properties of the finished Equation -1 wherein R and R are aliphatic hydrocarbyl radicals, R is a hydrocarbylene radical, R and R,-, are aromatic hydrocarbylene radicals and X is O or Not only do the grease compositions of the invention have high dropping points, but in addition they have excellent mechanical and thermal stability, and high temperature bearing performance properties as well. These excellent qualities are believed attributable in large part to the unique dibenzimidazole structure of the present thickening agents which produces as extremely stable molecule.

DESCRIPTION OF THE PREFERRED EMBODIMENTS NO N N NO 4 2 2 R3 N N/ H H OI Equation 2 NR N /N NH 6H C-R -c iao N N H H Equation 3 H II OCN-R -NCO R Ol-I R -O-C-N-R NCO Equation (11 2(111) 9a H911 N HQH HE? R -OC-N-R -N-C-N- N-C-N-R -N-C0-R 3 N N H g H Preparation of Dibenzimidazole-Urea Thickener's Equation 5 v OCN R NCO R H 9 H (5) NH R N-C-N-R NCO Equation 6 (II) 2 (V) 119a HQH N N HQ 9 R N-C-N-R -N-C-N- -N-C-N-R -N-CN.R 1 l 5 2 3 N N H H An alternative method of preparing the bisnitrobenzimidazole (intermediate product l) employed in Equation 2 is to react the dicarboxylic acid or its anhydride with two moles of a phenylene diamine which is not-nitro-substituted. The resultant product can be subsequently nitrated to produce bisnitrobenzimidazole which is then converted to its amino form (intermediate product ll) and reacted with two moles of intermediate products ill or V as shown in Equations 4 and 6, respectively. A more detailed description of the preparation of the benzimidazole thickeners is given in the examples.

Dicarboxylic acids or anhydrides which can be suitably employed in preparing the thickeners of the invention include the acids or anhydrides of aliphatic dicarboxylic acids such as succinic, glutaric. adipic, pimelic. suberic. azelaic. sebacic acids or anhydrides, as well as the anhydrides of aromatic dicarboxylic acids such as phthalic isophthalic 0r terephthalic acids or anhydrides or their esters. Cyclohexane dicarboxylic acids and anhydrides such as 1.2- or l.4-cyclohexane dicarboxylic acid or anhydride are likewise suitable as is tetrahydrophthalic acid or anhydride. Hydrocarbyl substituted dicarboxylic acid anhydrides can also be employed for example. alkylor alkenyl-substituted succinic corresponding to the formula is an alkyl or alkenyl substituent of from one to 16 carbon atoms or more. Aliphatic dicarboxylic acid anhydrides are preferred, and in general are selected so that the R radical of the previously depicted formula has from 2 to 20, preferably from 2 to 12 carbon atoms.

Phenylene diamines suitable for preparing the thickening agents of the invention are ortho-phenylene diamines having a nitro group substituted thereon, e.g., 4-nitro-o-phenylene diamine. In addition to the nitro substituent, o-phenylene diamines having other substituents, e.g., alkyl or halo substituents, can also be employed provided that such substituents do not appreciably interfere with the reaction of the phenylene diamine with the dicarboxylic acid anhydride.

if the alternative procedure discussed above is employed to prepare the bis-nitrobenzimidazole intermediate, the phenylene diamine need not contain a nitro substituent since the addition of the nitro groups is accomplished subsequent to formation of the bisbenzimidazole. Hence, when this procedure is followed, unsubstituted o-phenylene diamine may be utilized or any other o-phenylene diamine having substituents which will not appreciably interfere with the formation of bis-benzimidazole or its subsequent nitration. Specific examples of such phenylene diamines include 4-chloro-o-phenylene diamine and 3,4-toluene diamine.

Aromatic diisocyanates which may be employed in accordance with the invention include mono or dinuclear aromatic diisocyanates having a total of from six to 20 carbon atoms. Such diisocyanates include biphenylenediisocyanates. naphthylenediisocyanates and monophenylenediisocyanates including tolylenediisocyanate. Illustrative of such diisocyanates are 3,3-dimethylbiphenyl-4,4-diisocyanate diphenylmethane-4.4-diisocyanate, 3,3-dimethyldiphenylmethane-4,4-diisocyanate. 2,4-tolylenediisocyanate, 1,5- napthylenediisocyanate and mixtures of 2,4- and 2,6- tolylenediisocyanates. 2,4-Tolylenediisocyanate and mixtures of 2,4- and 2,o-tolylenediisocyanates are particularly preferred diisocyanate reactants.

Monohydric alcohols which can be suitably employed to prepare the dibenzimidazole-diurethanediurea thickeners include alphatic alcohols having from eight to 30, preferably from 12 to 24, carbon atoms. Examples of such alcohols include octyl, nonyl. lauryl,

tetradecyl, hexadecyl, octadecyl, octadecenyl, eicosyl and docosyl alcohols. etc., and mixtures thereof. Thickeners prepared using stearyl or oleyl alcohols or mixtures thereof have been found to be particularly advantageous.

LII

Monoamines which can be employed to prepare the dibenzimidazole-urea thickeners of the invention are aliphatic monoamines or those having a predominantly aliphatic character having from eight to 30, preferably from 12 to 24, carbon atoms. Suitable monoamines include octylamine, decylamine, dodecylamine, tet- 6 radecylamine hexadecylamine, heptadecylamine, octadecylamine, octadecenylamine, eicosylamine. docosylamine, tetracosylamine, etc. and mixtures thereof.

Mixtures of the above-mentioned monohydric alcohols and monamines can also be employed thereby producing benzimidazole compounds having both alkylurethane and alkylurylene terminal groups.

The thickening agents of the invention are generally employed in grease compositions 'in an amount sufficient to gel the oleaginous base vehicle to grease consistency. This amount can vary, for example, from about 550% by weight of the total composition. Normally, however, thickener concentrations of 10-35% by weight are sufficient to impart the desired consistency to the inventive compositions.

A wide variety of lubricating oils may be employed as the base vehicle in the present compositions. Suitable base oils include mineral lubricating oils such as naphthenic base, paraffin base or mixed base oils having a viscosity in the range of from SSU at F to 300 SSU at 210F; synthetic hydrocarbon oils such as oligomerized alpha-olefins and oils derived from coal products; synthetic oils such as alkylene polymers, alkylene oxide-type polymers, polyalkene glycols, polyethers, phosphate esters, dicarboxylic acid esters and pentaerythritol esters. The above oils may be used inidvidually or in mixtures thereof, wherever miscible or made so by the use of solvents. Of the aforementioned base oils, mineral lubricating oils having viscosities of from about 400 to 700 SSU at l00F are especially preferred.

ln addition to the dibenzimidazole thickeners, the present compositions can also contain anti-corrosion additives such as disodium sebacate, glyceryl monooleate. sodium sulfonates, sodium nitrite, aminoand benzo-triazoles, and isostearamides or imidazolines of tetraethylenepentamine; oxidation inhibitors such as phenyl-alpha-naphthylamine, phenyl-betanaphthylamine, diphenylamines, phenothiazine, dithiocarbamates and various analogs and homologs thereof; viscosity index improvers such as methacrylate polymers and copolymers; extreme pressure agents, and

any other additive recognized in the art to perform a particular function or functions.

The following examples illustrate the method of preparation of the present thickeners and their excellent properties. It is to be understood, however, that these examples are presented for illustrative purposes only and that the invention in its broader aspects should not be limited thereto.

EXAMPLE 1 Preparation of Dibenzimidazole-Urea-Urethane Thickening Agents A 4-liter round bottom flask was charged with 302.2 g (2 moles) of 4-nitro-o-phenylene diamine, 100.0 g (1 mole) of succinic anhydride and 2 liters of4 normal hydrochloric acid solution. The flask and its contents were then refluxed, with stirring for 24 hours. Heating was discontinued was the reactants were cooled to 0C. filtered, and the filtrate was discarded. The precipitate was collected and neutralized with 1,500 ml of 5 normal ammonium hydroxide solution, refiltered, and washed twice with water. The neutralized material resulting was dissolved in refluxing ethylene glycol. treated with decolorizing charcoal, filtered and the filtrate cooled. The crystalline precipitate that appeared was collected, washed with ethanol and dried. The yield was 65 grams of l,2-bis(S-nitrobenzimidazoyl- 2)ethane having a melting point of 305C.

56.04 g (0.16 mole) of the above product was then suspended in 1,200 ml of 3 normal hydrochloric acid solution to which was added palladium on charcoal catalyst and reduction of the nitro groups effected in a low pressure hydrogenation apparatus. The catalyst wasthen filtered off. the filtrate neutralized with sodium bicarbonate and the resulting precipitate collected. After washing with water and drying, 41.5 g of l,2-bis(5- aminobenzimidazoyl-Z)ethane hydrate was obtained having a melting point of l54155C.

A 5-liter 3-necked flask equipped with a mechanical stirrer was charged with 2 liters of chloroform and 522 g (3 mole) of commercial grade 2,4- tolylenediisocyanate. To this stirred solution was added 270 g (1 mole) of stearyl alcohol over a period of 2 hours. After the addition, the contents of the flask were poured into 3 liters of hexane and cooled overnight. The resulting precipitate, N-(3-isocyanato-4-methylphenyl)octadecyl carbamate, was collected and reprecipitated from hexane and vaccum dried. The product had a melting point of 78-79C.

17.54 g (0.06 mole) of the previously formed 1,2- bis(S-amino-benzimidazoyl-Z)ethane was placed into a 500 ml resin flask equipped with a mechanical stirrer together with 53.4 g (0.12 mole) of N-(3-isocyanato-4- methylphenyl)octadecyl carbamate in 573 g of HVl neutral oil having a viscosity of 70 at 210F. This suspension was heated with stirring, under nitrogen, to 127C. When the reaction was complete, the contents were cooled to approximately 1 C. The formulation was them milled three times in a three-roll paint mill. The resulting grease (Grease 1) contained 11.0% by weight thickner and had an ASTM unworked penetration (P of2l2 and a worked penetration (P60) of 264.

EXAMPLE [1 Preparation of Dibenzimidazole-Urea Thickening Agents The procedure of Example 1 was essentially repeated except that 269 g (1 mole) of stearylamine was reacted with 2,4-tolylenediisocyanate in place of stearyl alcohol thereby forming N-(3-isocyanato-4-methylphenyl) octadecyl carba'mide.

35.5 g (0.08 moles) of the carbamide intermediate was then reacted with l 1.7 g (0.04 mole) of 1,2-bis(5- aminobenzimidazoyl-2-)ethane prepared as in Example 1 in 382 g of a HVl neutral oil having a viscosity of 70 at 210F. After completion of the reaction, the contents were cooled and milled three times in a three-roll paint mill. The resulting grease (Grease 2) contained 1 1.0% by weight thickener and had an ASTM unworked penetration (P of 268 and a worked penetration (P of 283.

EXAMPLE Ill The procedure of Example 1 was essentially repeated except that a :40 molar ratio of stearyl and oleyl alcohols were employed in place of the stearyl alcohol reactant in Example 1. The resulting grease contained 9.5% by weight thickener and had an ASTM unworked penetration (P of 197 and a worked penetration (P of 253.

EXAMPLE IV The procedure of Example 1 was essentially repeated with the exception that an oligomerized alpha olefin synthetic hydrocarbon oil having a viscosity of 7.7 centistokes at 210F was employed in place of the mineral lubricating oil The resulting grease (Grease 4) contained 14% by weight thickener and had an ASTM unworked penetration (P,,) of 242 and a worked penetration (P of 275.

EXAMPLE V In order to demonstrate the excellent high temperature performance characteristics of the present grease compositions, the greases of Example 1 and 111 were subjected to two different high temperature bearing tests. The results of these tests are shown in the following table.

'lncludcs 1% wt phcnyl-alpha-naphthylaminc. 0.5'7: Oronilc 250 (diluuryl sclcnidc). 1'1 wt sodium schacate and 0.03% wt 3-amino-l.2 4 lriazole. Avcragc of two runs.

EXAMPLE V] Other dibenzimidazole thickeners and greases in accordance with the invention include those shown in the following table.

anhydride 9 l0 Table II Continued Grease C om- Acid or Phcnylene Alcohol Base position Anhydride Diamine Diisocyanate or Amine Oil 30% mole N L-5 8 Dodecyl 4-Nitro-o- 3.3-dimethyl- 100% mole B succinic phenylene hiphenyl-4.4'- C H 01! anhydride diamine diisocyanate 9 Phthalic 4-Nitro-o- 2,4-tolylene- 75% mole anhydride phenylene diisocyanate C H OH C diamine 25% mole m aa Base Oil A Minural lubricating oil having a it of 500 SSU at l()()F. Basc Oil B Mineral lubricating oil having a viscosity at 70 SSU a5 2lUF, Base Oil (I Mixture of hcxadcql isostearatc and dimer acid esters.

I claim as my invention:

1, A dibenzimidazole compound corresponding to the formula:

wherein R, and R are aliphatic hydrocarbyl radicals having six to 30 carbon atoms. R;, is a hydrocarbylene radical having from two to 20 carbon atom. R and R are aromatic hydrocarbylene radicals having from six to 20 carbon atoms and X is --O or 2. The compound of claim 1 wherein X is O--.

3. The compound of claim 1 wherein X is 4. The compound of claim 1 wherein R is an alkylene radical having two to 12 carbon atoms.

16 to 18 carbon atoms. 

1. A DIBENZIMIDAZOLE COMPOUND CORRESPONDING TO THE FORMULA:
 2. The compound of claim 1 wherein X is -O-.
 3. The compound of claim 1 wherein X is
 4. The compound of claim 1 wherein R3 is an alkylene radical having two to 12 carbon atoms.
 5. The compound of claim 1 wherein R1 and R2 have from 12 to 24 carbon atoms.
 6. The compound of claim 5 wherein R4 and R5 are tolylene.
 7. The compound of claim 6 wherein R3 is ethylene.
 8. The compound of claim 7 wherein R1 and R2 have 16 to 18 carbon atoms. 